Identification of Feedback in Pollutant Pathway Models

Abstract

In many studies involving problem substances several pathways through the various compartments of the environment are relevant. In order to rank different pathways or to evaluate mitigation measures, numerical modeling can be an appropriate tool. Global, regional, or local compartment models, foodweb models, transport dispersion models, and geochemical speciation models have common features. At several levels (compartments, processes, species) such models can be characterized by directed graphs. Using graph-theoretical results a criterion for feedback as a relevant model property is formulated. If there is feedback within a model, phenomena are usually more complex, which has to be taken into account by numerical approaches. This places demands on computer resources. The graph-theoretical approach is illustrated on mercury as an example problem component.